I agree with what many people are saying here. 2 quads in the SP it's too risky, land them and your scores will soar, miss them and you can basically kiss the podium goodbye. On the other hand, with a solid SP as buffer, you can go for it in the FP, if you fail, you have your SP and the other FS jumps as cushions.
Hanyu (who misses his 4S more often than not and is already struggling with the combo on the SP) and Fernandez (who has also not been that consistent on the 4S lately) don't need to risk it so much because their skills and reputation give them good PCS that make up for it, both of them have SP full of transitions and difficult step sequences. Aside from the GOEs, for example, you can't possibly tell me that Kovtun and Hanyu have the same quality in, say, the 3A. So Kovtun needs to make up for those points, where other skaters have the upper edge in skills and GOEs, with another quad. But they're ambitious guys, so maybe when they get more consistent (consistent enough to get positive GOEs most of the time), and have the need to incorporate them to stay on top (there are many that don't even have a quad in the SP yet), they will. 2 quads is also a risk to the skater's health, so there's no reason for them to risk it when they don't have the need.
Hanyu (who misses his 4S more often than not and is already struggling with the combo on the SP) and Fernandez (who has also not been that consistent on the 4S lately) don't need to risk it so much because their skills and reputation give them good PCS that make up for it, both of them have SP full of transitions and difficult step sequences. Aside from the GOEs, for example, you can't possibly tell me that Kovtun and Hanyu have the same quality in, say, the 3A. So Kovtun needs to make up for those points, where other skaters have the upper edge in skills and GOEs, with another quad. But they're ambitious guys, so maybe when they get more consistent (consistent enough to get positive GOEs most of the time), and have the need to incorporate them to stay on top (there are many that don't even have a quad in the SP yet), they will. 2 quads is also a risk to the skater's health, so there's no reason for them to risk it when they don't have the need.